I just ran into the same problem. AutoSave gave me an error saying that the file is locked. I got around the issue by moving the existing file to Trash. I was then able to save the most recent file manually. By the way, there isn't a "Save As" option on Mac.
**Update - I guess it wasn't a solution. Although I clicked "Save" and it appeared that a new file was created, I didn't see the file in Finder. I recovered the original file from Trash and it seems to have all of the updated info?
